This invention relates to a thermoplastic tackifying hydrocarbon resin copolymer which is the product of the copolymerization of an isoolefin such as isobutylene or diisobutylene with a diolefin such as piperylene.
It is known from U.S. Pat. Nos. 2,753,325; 3,467,632; 3,577,398; 3,622,551; 3,639,366; and Belgium patent No. 784,518 that hydrocarbon resins can be prepared from the polymerization of a mixture of diolefins and monolefins. However, these prior patents do not suggest the use of a minor amount of isobutylene of diisobutylene and/or are relatively more expensive then the resins of this invention.
In regard to Belgium patent No. 784,518, this discloses an elastomer made from a major amount of isobutylene and a minor amount of isoprene or piperylene.
In regard to Patent No. 3,577,398, the present invention is a distinct improvement thereover in that it has been found that the C.sub.5 monoolefin, 2-methyl-2-butene used therein can be replaced with the more economical monoolefins, isobutylene or diisobutylene to achieve substantially the same tackifying resins.